Don't look it like that, look at the emotional connection of the action. Kissing is one thing that kind of seals the deal for how a lot of relationships start. I can tell you right now, for probably 90% and don't quote me, of women, a bad kiss is a deal-breaker for moving forward. Kissing brings passion so I definitely understand why it is off limits. That being said, for many, they cherish that and don't want it soiled so to speak.